1. Technical Field
The present invention relates to a carbon fiber-reinforced silicon carbide composite material and a method of preparing the same.
2. Description of the Related Art
A melt infiltration (MI) process is one of several methods of preparing a fiber-reinforced silicon carbide composite material, and is characterized in that a product can be very easily produced because of short process time and low production cost.
Generally, a melt infiltration (MI) process includes the steps of: 1) impregnating a fiber with a polymer to form a fiber-reinforced plastic and then curing the fiber-reinforced plastic; 2) carbonizing the cured fiber-reinforced plastic under an inert atmosphere; and 3) melting metal silicon and then infiltrating the molten metal silicon into the carbonized fiber-reinforced plastic to prepare a fiber-reinforced silicon carbide composite material.
In this case, the carbonized fiber-reinforced plastic is a porous fiber-carbon composite material, and the molten metal silicon is infiltrated into the carbonized fiber-reinforced plastic through pores by capillary force. However, when the size of pores of the carbonized fiber-reinforced plastic is large, a free metal, which cannot participate in a reaction, exists between the infiltrated molten metal silicon and the carbon contained therein, and an unreacted metal region (metal river or metal pool) is formed.
Due to such an unreacted metal region, the prepared fiber-reinforced silicon carbide composite material exhibits low strength, and particularly, the strength thereof is rapidly lowered at high temperature, thus deteriorating the high-temperature characteristics thereof.
Meanwhile, Korean Patent Registration No. 10-0689636 discloses a method of preparing a carbon fiber-reinforced silicon carbide composite by uniformly applying thermosetting resin powder and ceramic powder onto a carbon fiber and then performing a metal silicon melt-infiltration process. However, this method is problematic in that a free metal, which cannot participate in a reaction, exists between the infiltrated molten metal silicon and the carbon contained therein, thus deteriorating the strength of the carbon fiber-reinforced silicon carbide composite.